You see them all the time in the news - the number of people who were in the hospital last year, the percentage of kids who are overweight, the rate at which people are catching the flu, the average cost of a medical procedure. These are all types of health statistics.
Health statistics are numbers about some aspect of health. Statistics about births, deaths, marriages, and divorces are sometimes called "vital statistics." Researchers use statistics to see patterns of diseases in groups of people. This can help in figuring out who is at risk for certain diseases, finding ways to control diseases and deciding which diseases should be studied.